Toyota Repair: rough idle/stalling, toyota sr5 pickup, fuel pressure regulator

Question
I have a 92 Toyota SR5 Pickup (3.0 V6 4WD),It idles very rough and when you shift from park to other gears it idles up or down.I have replaced the plugs,wires distributor cap,rotor button fuel filter and expensive oxygen sensor.It has recently started stalling when i come to a stop or shift from drive to park.I have listened to others and replaced what I mentioned now I hear it could be a injector or fuel pressure regulator.It is getting costly.PLEASE HELP

Answer
The very first thing you should do now is to have the engine compression checked, it is possible that there is a loss of compression due to a leaking valve, have that done and contact me with the results, you may also contact a toyota dealer, there was a special service campaign to replace headgaskets on these engines at no cost to you, have your VIN# ready when you call them to find out if the campaign has beed done and if it applies to your truck.